//  join不改变原数组
let arr = new Array()
arr[0] = 155
arr[1] = 466
let arr1 = arr.join("&")
console.log(arr1);
console.log(arr);

arr1 = [123, 2, 35, [15, 5], 232]
let arr2 = arr1.join("")
console.log(arr2);